We propose to quantitate gastric epithelial cell function and morphology during initiation of erosive gastritis by a variety of stressors. Gastric surface cell turnover will be correlated with granule content and characterization of mucus. Blood flow to intimate sites of potential ulcerogenesis will be monitored by infra-red etection and fluorescent excitation analysis. Cyclic AMP and GMP will be measured in surface cells before and after exposure to stressors (aspirin, hemorrhagic shock, and endotoxin). These studies are designed to characterize early change in epithelial function prior to injury and subsequent desquamation of cells so typical of erosive gastritis. BIBLIOGRAPHIC REFERENCES: Cheung, L.Y., Reese, R.S. and Moody, F.G.: Direct effect of endotoxin on the gastric nucosal microcirculatotion and electrical gradient. Surgery 79 (5): 564-568, 1976. Moody, F.G., Cheung, L.Y., Simons, M.A., and Zalewsky, C.: Stress and the acute gastric mucosal lesion. Am. J. Dig. Dis. 21(2): 148-154, 1976.